1. Field of Invention
The present disclosure relates to a display apparatus and, in particular, to a three-dimensional (3D) image display device.
2. Related Art
In general, three-dimensional (3D) image display apparatuses are categorized into stereoscopic display apparatuses and autostereoscopic display apparatuses (also referred to naked-eye type 3D image display apparatuses). Regarding to the stereoscopic display apparatus, the user has to wear a viewing aid, such as shutter glasses, so that the left and right eyes of the user can receive different images respectively, and thereby perceiving a 3D image. Regarding to the autostereoscopic display apparatus, a specially designed optical element, such as a parallax barrier, is configured so as to allow the display apparatus to provide different images to the left and right eyes of a user respectively, so that the user can perceive a 3D image by naked eyes.
FIG. 1 is a schematic diagram of a conventional autostereoscopic display apparatus 1, which includes a display panel 11 and a parallax barrier 12. The display panel 11 includes two substrates 111 and 112, and a liquid crystal layer 113 sandwiched therebetween. In addition, the substrate 111 has a pixel array consisting of a plurality of pixels (not shown) disposed thereon. Each pixel corresponds to at least one liquid crystal cell (e.g. the liquid crystal cell 113a or 113b) of the liquid crystal layer 113. The parallax barrier 12 includes two substrates 121 and 122 opposite to each other, liquid crystal cells 123 and 124 disposed between the substrates 121 and 122, two sets of strip electrodes 125 and 126 arranged alternately on a surface of the substrate 121, and a surface electrode 127 disposed on a surface of the substrate 122.
When the surface electrode 127 and the strip electrode set 125 are grounded and the strip electrode set 126 is connected to a high voltage, the liquid crystal cells 123 corresponding to the strip electrode set 125 are not driven, and the liquid crystal cells 124 corresponding to the strip electrode set 126 are driven. As such, when the light rendered by the display panel 11 passes through the parallax barrier 12, the light cannot pass through the driven liquid crystal cells 124 and can merely pass through the non-driven liquid crystal cells 123. Therefore, the image rendered by the display panel 11 would be transformed into an image with a parallax barrier pattern that is capable of providing a left-eye image (such as the image from the pixels corresponding to the liquid crystal cells 113b) and a right-eye image (such as the image from the pixels corresponding to the liquid crystal cells 113a) respectively to a user's left and right eyes. Upon receiving the signals of the left- and right-eye images, the user's brain may perceive a 3D image.
Nowadays, many display devices can rotate with respect to a base or a body of an electronic device. For example, a display apparatus is under a landscape mode when it is horizontally oriented (that is, the long side of the display apparatus is oriented to be horizontal); otherwise, a display apparatus is under a portrait mode when it is vertically oriented (that is, the long side of the display apparatus is oriented to be vertical).
However, the parallax barrier 12 of the conventional 3D image display apparatus 1 employs liquid crystal cells to form the light-shielding structure. When operating under the portrait mode, even if an opening ratio of the parallax barrier is optimized to reduce the moiré and color shift issue, the liquid crystal cells in the proximity of the peripheral of the electrodes may not be rotated completely or the distribution thereof may be uneven. Accordingly, the users may suffer from the color shift and moiré issues due to the difference of the viewing angles, thereby affecting the entire displaying effect.
Therefore, it is an important subject to provide a 3D image display apparatus that can reduce the moiré issue and prevent the color shift, thereby improving the displaying effect.